Non-woven random web filamentary materials are well known and provide useful physical properties over woven or oriented webs. In general, randomly aligned filaments form a web material with an open convoluted mesh that can be useful in ventilating and filtering, but have an essentially equal strength in both lateral and transverse directions that is not found in other bonded webs where the filaments are oriented in particular direction.
Although there may be various techniques for producing randomly oriented webs, a common technique is by using commercial machines called a Rando-Feeder and Rando-Webber, which operate together to separate the filaments and trap them in random alignment (a more detailed description is given in Man-Made Fibers, sixth edition, by R. W. Moncrief, at pages 774-5). The randomly aligned filaments are then bonded together at their intersections by adhesive binding agents, or by thermoplastic or solvent bonding of the fibers themselves. Generally the filaments are synthetic fibers, and the particular synthetic material and its denier is selected to meet the requirements for the particular application in which the web will be used. Similarly, the binding agent or agents are chosen to suit the application.
For example, in U.S. Pat. No. 5,167,579 by this inventor, a unitary mat of such randomly aligned material is disclosed for use in a roof ridge vent. The fiber material and its denier, the binder, fiber percentage and other parameters of that mat were chosen to suit the requirements of providing adequate ventilation, acting as a water and insect barrier, resisting deterioration for approximately the life of the roof under normal environmental conditions, and supporting the cap shingles. Other applications, such as packaging liners, pressure filters, heat exchange liner, splash block in cooling towers, battery plate separators, pallet separators, sound attenuators, etc., may dictate a different choice of materials.
While a random web material is frequently useful because it can provide a relatively open mesh without sacrificing lateral and transverse tensile strength, it generally will not resist compressive forces to the same extent. That is, it is more easily compressed than stretched or ripped apart. This may be a constraint in applications where the material is subjected to significant compressive force. For example, in the application of a roof ridge vent, the mat of randomly aligned material is relatively thin (5/8") to create a low-profile appearance of the capping shingles along the ridge, yet is sufficiently air permeable to permit the necessary ventilation. With asphalt shingles or other relatively light capping elements, even when covered by snow, the weight on the mat will not compress the material to any significant extent which might interfere with ventilation flow. However, if very heavy slate or stone tiles are used as the ridge cap, the material may compress to the extent that the ventilation is restricted, unless the thickness of the mat were increased, or a larger denier fiber and stiffer binding agents selected to support the heavier weight. Similarly, if the material is used as a pallet separator to cushion and ventilate between heavy cargo pallets, it must resist severe compressive while retaining an open mesh for ventilation. In these and other applications, it would be advantageous to provide an essentially compression-proof random web material.
This invention is related to the compression resistant solution disclosed in international application PCT/US92/06658 by this inventor, wherein solid nylon cores are injected into the vent mat at spaced intervals to form a support grid to carry the weight of slate capping tiles. In particular, this invention is directed to a method of injecting quick-setting liquid polymer into the filamentary web materials to form plastic pins which are bonded to the filaments.